Semiconductor devices, especially power semiconductor devices such as power semiconductor switches often include a temperature measurement functionality for detecting faulty or undesired mode of operations during which undesirably high temperatures may occur. Such faulty or undesired mode of operations may be, inter alia, an over-load, or a short circuit.
Power semiconductor switches capable of detecting over-temperature, over-load, short-circuits, etc. are often referred to as “smart power switches.” In known applications temperature is often measured at two positions, namely one temperature sensor measures the temperature in or close to the active area of the semiconductor device (e.g., of the DMOS switch) and another sensor measures the temperature in or close to the coldest area of the chip. The difference between these two temperature measures may be used to assess the state of the semiconductor device. That is, if the temperature difference exceeds a predefined threshold value or if one temperature measure exceeds a maximum allowable temperature, then the semiconductor device is powered down in order to avoid damage to the device. The mentioned temperature difference between the active area and a “cold spot” of the chip is also referred to as “relative temperature” and measured in Kelvin.
However, in some applications the mentioned threshold necessary for avoiding damage to the device might be too low compared to high (relative) temperatures resulting from relatively high inrush currents occurring during a start-up period of the device and consequently the over-current shut-down would be triggered indirectly by the unavoidable inrush currents.
Thus, there is still a general need for a semiconductor device including an over-temperature protection, which accounts for high inrush currents after switching on the device.